Query on speed difference using OOKLA

Hi,

I had recently did a speed test using the OOKLA speed test on my android phone and found that there are quite a big difference between the speed using the OOKLA speed test app and the built-in OOKLA speed test in the ORBI app. I would like to ask why are there difference in the speed when I had tested both at a same place and how could I increase the speed other than standing right in-front of the router as I had already done so.

OOKLA Speedtest APP:

Download speed: 351 Mbps, Upload speed: 206 Mbps

ORBI App by OOKLA Speedtest:

Download speed: 489.29 Mbps, Upload speed: 789 Mbps